The present invention relates to a seat structure for a vehicle, and more specifically to a seat structure for a vehicle in which a seat is capable of sliding in a vehicle longitudinal direction and a vehicle width direction.
Conventionally, a seat structure in which a seat, particularly a second row seat is configured so as to slide in the vehicle longitudinal direction and the vehicle width direction to improve utility of the seat is known.
Further, as such a seat structure in which the seat is capable of sliding slide in the vehicle longitudinal direction and the vehicle width direction, a seat structure (so-called long slide) in which there is provided a long sliding distance in the vehicle longitudinal direction to materialize a variety of seat arrangements is also known. In this case, a vehicle-longitudinal-direction slide rail should be longer than a vehicle-width-direction slide rail. Accordingly, the following structure is considered preferable to provide a proper supporting rigidity of sliding mechanisms. Namely, a vehicle-longitudinal-direction sliding mechanism is disposed on a vehicle floor, a vehicle-width-direction sliding mechanism is supported on this vehicle-longitudinal-direction sliding mechanism so as to slide on it, and a vehicle seat is supported on the vehicle-width-direction sliding mechanism. An example of this type of seat sliding mechanism is disclosed in Japanese Laid-Open Patent Publication No. 10-203210.
Meanwhile, there is also a need as a variation of seat arrangements that a seat is configured such that a seat back is folded on a seat cushion to provide a space for a load compartment above a back face of the seat back. However, simply rotating the seat back about one rotational axis forward could not provide the seat back with its horizontally-positioned back face when the seat back has been folded because of shapes of the seat cushion and the seat back. Accordingly, a certain design that a front of the seat cushion is lowered a little according to a forward rotation of the seat back is necessary when this kind of foldable seat is used.
Namely, in the case where the foldable seat is combined with the structure (a structure materializing both a so-called long slide and a vehicle-width-direction slide of a seat) disclosed in the above-described patent document to improve the seat utility further, the vehicle-longitudinal-direction sliding mechanism, the vehicle-width-direction sliding mechanism and the mechanism lowering the seat cushion need to be interposed between the vehicle floor and the seat. However, since the seat cushion is lowered when the seat is folded, there occurs a problem that the vehicle-width-direction sliding mechanism interferes with the seat cushion being lowered. Meanwhile, there exists an idea that the seat cushion and the seat back are connected through a double-hinged mechanism in order to provide the seat back with its horizontally-positioned back face when the seat back has been folded by avoiding the interference of the vehicle-width-direction sliding mechanism with the seat cushion. However, there would occur another problem that a height of a floor face of a load compartment which is formed above the back face of the seat back is high improperly.
Further, in the case where a lowering mechanism for the seat cushion is disposed below the seat cushion, particularly around a rear end of the seat cushion below the seat cushion, an enough thickness of the seat cushion would not be obtained, thereby deteriorating comfortable sitting of the seat.